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The worldwide burden of valvular heart disease (VHD) continues to grow due to increases in life expectancy combined with the high incidence of rheumatic heart disease in developing nations.1 Patients with VHD and certain comorbid conditions or prosthetic heart valves (PHVs) are at high risk for thromboembolic complications and often require antithrombotic therapy (Table 81–1). Although bleeding is a risk with all antithrombotic agents, the frequency and consequences of a stroke make drug therapy appropriate in many patients with VHD.2,3

Antithrombotic therapy among individuals with native valve disease, defined by the authors as VHD in the absence of PHV or mitral stenosis, is based on the presence of concomitant risk factors (Fig. 81–1). The most common risk factors include atrial fibrillation and left ventricular systolic dysfunction.

Atrial Fibrillation

Multiple randomized controlled trials have demonstrated the clinical benefits of antithrombotic therapy with either warfarin or aspirin compared with placebo or no treatment in reducing ischemic events among individuals with "nonvalvular" atrial fibrillation.4,5 Based on a meta-analysis of >28,000 patients comprising 29 trials, adjusted-dose warfarin therapy was associated with a 60% and 40% reduction in ischemic stroke compared with placebo and antiplatelet therapy, respectively.5 A recently completed trial found that the addition of clopidogrel to aspirin also reduced ischemic events, including stroke, among patients with atrial fibrillation who were unsuitable for vitamin K antagonist therapy.6 The benefits of anticoagulation are graded, increasing as the risk for ischemic stroke increases. Multiple risk stratification schemes exist for guiding clinicians in assessing stroke risk among individuals with nonvalvular atrial fibrillation.7-10 In summary, warfarin is recommended in any atrial fibrillation patient who has had a systemic embolus. It is also recommended in those with two or more of the following: diabetes mellitus, a history of hypertension, coronary artery disease, congestive heart failure, and age >75 years. Those with none or only one risk factor can reasonably be given aspirin 325 mg/d as an alternative.11